1998 Ford Taurus Transmission and speedometer problem

5F36P2

MEMBER
1998 FORD TAURUS
6 CYL
FWD
AUTOMATIC
61,396 MILES

I recently bought a 1998 Ford Taurus with the Duratec 200 h.P. Engine. As I was driving the " overdrive " light started flashing, and the speedometer dropped to "zero" for a few seconds and then started working intermittently. The transmission then felt like it slipped into "neutral" for a few seconds and revved up to 3500 rpm's. A second or so later the car slipped back into gear. I brought the car to my mechanic and he said the problem was caused by a faulty speed sensor. He replaced the sensor and for a few hours everything was fine. The next day the same problem with my speedometer and transmission started all over again, only this time the "overdrive " light did not flash. I went back to my mechanic and he said nothing was showing up on his diagnostic test. He referred me to a transmission specialist who also ran diagnostics and said nothing was showing up. He suggested that maybe the problem was that the transmission was heating up due to a clogged or cracked transmission filter and that I should replace both, even though both mechanics said the fluid looked fine. Desperate, and running out of money, I changed the transmission fluid and filter. The same problems still kept happening with the transmission and speedometer. About a week later, the "overdrive " light started blinking along with the transmission and speedometer problems, only this time the "overdrive " light would only stay on for about a minute and then turn off : however the transmission continues to feel like it is slipping for a few seconds as it revs up to about 3500 r.P.M.S and the speedometer fails for a short time over and over. The other day, as I sat in my car idling in "park" I revved the engine and as it neared the 4000 r.P.M. Mark it started to lose r.P.M.S no matter how hard I stepped on the accelerator. It was almost as if there was some type of "governor" on the car that prevented it from going over a certain speed. I am at my wits end with this problem and this is our family's only car. I can not afford to bounce from shop to shop as this will cause a tremendous financial burden on us. Could you please help us.
Respectfully,
J.

2 Replies

FLEXY5

MECHANIC
512 POSTS

I would be interested to know what the code is for the O/D light now. There are a couple of things to be considered. The first thing that comes to mind is a wiring concern. There may be a problem with the wire connector at the sensor. Check the connector to make sure it is seated properly. Also inspect the wire harness from the sensor and make sure it is not grounding or chafing on anything. This could also cause a problem with the sensor readings. The symptoms are typical of a failed speed sensor, but if it was replaced and we still have the same issue, we need to start looking elswhere. It is possible that the new sensor is bad, but it is a rarety. As far as the reving in park, it does have a rev limiter built into the PCM. It is not adjustable.